Fix lint: simplify multi-line assert string

Signed-off-by: Justin Chu <justinchu@microsoft.com>

Author: justinchuby

src/mobius/integrations/ort_genai/genai_config_test.py

@@ -761,6 +761,4 @@ def test_cuda_ep_all_blocks_have_cuda_session_options(self):
             session_opts = config["model"][block]["session_options"]
             provider_options = session_opts["provider_options"]
             assert len(provider_options) == 1, f"{block} missing CUDA provider options"
-            assert "cuda" in provider_options[0], (
-                f"{block} has wrong EP in provider_options"
-            )
+            assert "cuda" in provider_options[0], f"{block} has wrong EP in provider_options"